I have a Arduino deiecimila board and I have an atmel 168 chip on a breadboard. I can program the chip and place it on the breadboard and it works fine. I was wondering if there was any way to program the atmel chip using the rx and tx pins on my diecimila. Hooking them up failed and I was wondering what could be going wrong or if this was even possible. I would prefer to utilize the usb to serial converter on the decimila instead of buying another chip and breakout board.
Option 1: remove the ATmega from your decimilla board and use pins 0 and 1. This reduces your Decimilla board to a TTL level rs232/usb adapter.
Option 2 (if you have a serial port of some flavor): use a MAX232 (or other) rs232 transceiver chip and a DB9 connector to give it a standard serial interface. You can also use some transistors, caps and resistors to do do more or less the same thing. Check Arduino Serial documentation for transistor circuitry, and any MAX232 circuit example on the web (or in the maxim data sheet).
I suggest you the first option, using a Diecimila board without the Atmega, and hooking RX and TX pins.
But don’t forget you need to hook both GND pins too.
And don’t forget that you’ll need the bootloader on the the breadboard Atmega!
Would the RESET line have to be connected to the breadboard Atmega as well?
For auto-reset functionality, yes. Not sure how that circuit traces out, it may need looking at.
If you are resetting the breadboard arduino manually (with its own circuit), it isn’t needed.